Radiation belt electron dynamics at low L (<4): Van Allen Probes era versus previous two solar cycles

X Li; D. N Baker; H Zhao; K Zhang; A. N Jaynes; Q Schiller; S. G Kanekal; J. B Blake; M Temerin

doi:10.1002/2017JA023924

Back

Radiation belt electron dynamics at low L (<4): Van Allen Probes era versus previous two solar cycles

Journal article

Open access

Peer reviewed

Radiation belt electron dynamics at low L (<4): Van Allen Probes era versus previous two solar cycles

X Li, D. N Baker, H Zhao, K Zhang, A. N Jaynes, Q Schiller, S. G Kanekal, J. B Blake and M Temerin

Journal of geophysical research. Space physics, Vol.122(5), pp.5224-5234

05/2017

DOI: 10.1002/2017JA023924

Files and links (1)

url

https://doi.org/10.1002/2017JA023924View

Published (Version of record) Open Access

Abstract

Long-term (>2 solar cycles) measurements reveal that MeV electron fluxes, solar wind speed, and geomagnetic activity have been extremely low during this current solar cycle, including years before and during the Van Allen Probes era. This study examines solar wind speed, the geomagnetic storm index (Dst), >2 MeV electrons at geostationary orbit, and ~2 MeV electrons across various L shells measured by Solar Anomalous Magnetospheric Particle Explorer in low Earth orbit (LEO) and by the Van Allen Probes/Relativistic Electron and Proton Telescope (REPT) in a geotransfer-like orbit; the latter measurements are normalized to LEO based on comparison with Colorado Student Space Weather Experiment/Relativistic Electron and Proton Telescope integrated little experiment (REPTile) measurements in LEO. The average ratio of REPTile/REPT varies in a systematic manner with L, ~16% at L = 2.7, decreasing with L and reaching ~0.7% at L = 4.7, and increasing again with L though with greater uncertainty. We show that there have been no ~2 MeV electron enhancements inside L ~ 2.6 since 2006, prior to which numerous penetrations of ~2 MeV electrons into L < 2.5 were measured during periods of stronger solar wind conditions (in terms of high-speed solar wind, magnitude of interplanetary magnetic field, B, and a sustained southward Bz) and thus stronger geomagnetic activity. We conclude that results from the Van Allen Probes, which have been providing the finest measurements but in operation during a quiet solar activity period, may not be representative of radiation belt dynamics, particularly for the inner edge of the outer belt, during other solar cycle phases.

Details

Title: Subtitle: Radiation belt electron dynamics at low L (<4): Van Allen Probes era versus previous two solar cycles
Creators: X Li - University of Colorado Boulder
D. N Baker - University of Colorado Boulder
H Zhao - University of Colorado Boulder
K Zhang - University of Colorado Boulder
A. N Jaynes - University of Colorado Boulder
Q Schiller - Goddard Space Flight Center
S. G Kanekal - Goddard Space Flight Center
J. B Blake - The Aerospace Corporation
M Temerin - University of California, Berkeley
Resource Type: Journal article
Publication Details: Journal of geophysical research. Space physics, Vol.122(5), pp.5224-5234
DOI: 10.1002/2017JA023924
ISSN: 2169-9380
eISSN: 2169-9402
Grant note: DOI: 10.13039/100000001, name: National Science Foundation, award: AGS 1443749; DOI: 10.13039/100000104, name: National Aeronautics and Space Administration, award: NNX15AF56G, NAS5‐01072; DOI: 10.13039/100006602, name: Air Force Research Laboratory, award: FA9453‐14‐M‐0256
Language: English
Date published: 05/2017
Academic Unit: Physics and Astronomy; University College Courses
Record Identifier: 9984199791202771

Metrics

18 Record Views

39 Times Cited - Web of Science